This invention relates to electric motors and mounting apparatus therefor, particularly for direct drive blower motors, with minimized noise and vibration.
It has been common to mount motors within a blower housing by having mounting arms attached to the motor frame itself and the blower housing with a fan directly mounted on the motor shaft. Such systems may permit vibrations from the motor to be transmitted to the blower housing to a degree that results in objectionable noise. It has been recognized that the physical characteristics of the mounting arms can substantially affect the transmission of vibrations and generally that the more rigid the mounting system is the more vibrations are transmitted. In order to maintain the motor in a relatively fixed location for its intended driving function, while reducing transmitted vibrations, there have been many techniques developed over the years which provide flat sheet metal mounting arms located with their flat surfaces in a longitudinal direction. Such mounting arms provide axial and radial rigidity while having a high degree of torsional flexibility which has been found favorable for reduced vibration transmission.
The present invention relates to a mounting system of the general type described above in a particular form for achieving multiple advantages of convenience, economy, and capability. In accordance with this invention, the motor has a band encircling the motor body and fastened on itself for secure retention. The band is a unitary sheet metal element that lies flat against the motor and at a plurality of spaced locations has a pair of projections outwardly extending from the major portion of the band with apertures aligned parallel to the shaft axis. The apertures in the projections of the band accommodate a hinge pin running through the inner circular end of a mounting arm that has a torsionally flexible characteristic. The mounting arm has its other extremity adapted for fastening to a blower housing.
The preferred method of assembly of the mounting system is to form or obtain the band with the apertured projections as described above, orient the inner scrolled end of the mounting arm between the apertured projections of the band, insert the hinge pin through the band projections and the scrolled end of the mounting arm, fasten the hinge pin in place, preferably by riveting, and after all the arms have been so attached to the band to assemble the band on the motor body.
The favorable characteristics of the mounting system include its ability for use on a variety of motor frame types, including some of relatively open construction which have minimal or no area available for the attachment of mounting elements by welding. The present mounting system requires no welding whatsoever which is further favorable in that it avoids the need for any special care to prevent welding heat from damaging the characteristics of the torsionally flexible arms or other parts of the system.
The manufacture and supply of mounting arms, the band, or the band/mounting arm subassembly, may be separate from the motor itself. The pivotal mounting of the arms on the band permits them to be folded over after assembly during shipment or storage until they are needed on a motor. The band permits adjustment in its location along the motor body to any desired point and also facilitates replacement as needed after initial assembly.
The cost and convenience of use of the present mounting sysem is favorable as compared to other known flexible mounting systems while attaining dampening characteristics at least as good as other systems.